Phantom is a brand, so it depends on which country you are in (and as always in the case of the US, which state). If you buy your fireworks locally from a Phantom dealer, they are probably legal where you are.
Firecrackers are legal in the UK but fireworks are not Legal. So you can bye fireworks in the UK but not firecrackers.
No
Yes they are legal to purchase
yes
no
of course not
Yup.
Yes
Fireworks for personal use in the USA is restricted. For example, buying fireworks in Tennessee is legal. But, taking them into New Jersey is illegal. New Jersey has anti fireworks laws. Each US State has different regulations. As for US borders with Mexico or Canada, it's safe to say that it's illegal to take fireworks into the USA for personal use.
No.
Fireworks are meant for celebrations and fun! you can bring them to the party if legal in your state, but be careful you can get burnt.